1. Field of the Invention
The present invention relates to a substrate transfer method and a substrate transfer apparatus and, more specifically, to a substrate transfer method and a substrate transfer apparatus for a substrate, for example, a semiconductor wafer, LCD glass substrate, or the like.
2. Description of the Related Art
Generally, in the manufacture of the semiconductor device, the photolithography technology is used to form a thin film of ITO (Indium Tin Oxide) and an electrode pattern on a semiconductor wafer, LCD glass substrate, or the like (hereinafter, referred to as a substrate). In the photolithography technology, a photoresist is applied on the substrate, a resist film formed on the substrate by the application is exposed to light according to a predetermined circuit pattern, and the exposed pattern is subjected to developing treatment to for a circuit pattern in the resist film.
To perform such a series of treatments, a coating and developing treatment apparatus has been conventionally used. In the coating and developing treatment apparatus, treatment units for performing predetermined treatments on the substrate are provided, such as surface treatment, cleaning treatment, resist coating treatment, post-exposure developing treatment, and heating treatments before and after exposure, and so on.
A transfer apparatus is used for transfer of the substrate between these units, and is provided with a transfer arm (also referred to as a pair of tweezers) which is movable in the vertical direction, horizontal direction, and the horizontal rotation direction in which the substrate is transferred (carried-in, carried-out). A support member made of a synthetic resin for supporting the substrate without causing damage to the substrate is attached to the transfer arm. Further, the support member is set to have a size slightly larger than the outer dimension of the substrate, accommodating the error in dimension of the substrate so as to support the substrate and deliver the substrate to a substrate mounting means provided in each treatment unit (Japanese Patent Application Laid-open No. H11-243133).
Incidentally, in this kind of substrate transfer, it is demanded to deliver the substrate between the transfer arm and the mounting means at a high speed and with a high accuracy in order to improve the throughput and improve the yields.
However, if the substrate is transferred (carried-in, carried-out) to/from the treatment unit at a high speed and with a high accuracy, the behavior of the transferred substrate is unstable due to the inertial force when the transfer arm is moved to the treatment unit because the support member has a size larger than the outer dimension of the substrate as described above. This causes positional displacement of the substrate to degrade the treatment accuracy. For example, the problems are that
(1) the film thickness of the coating film becomes nonuniform in the coating treatment,
(2) the exposure at a predetermined peripheral portion of the substrate becomes nonuniform in the peripheral exposure processing of the substrate, and
(3) heating becomes nonuniform in the heating treatment, to fail to uniform the film thickness, causing a reduction in yield.